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1.
J Environ Manage ; 359: 120962, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38677229

RESUMEN

Low-water-level regulation has been effectively implemented in the restoration of urban river sediments in Guangzhou City, China. Further investigation is needed to understand the microbial mechanisms involved in pollutant degradation in low-water-level environments. This study examined sediment samples from nine rivers, including low-water-level rivers (LW), tidal waterways (TW), and enclosed rivers (ER). Metagenomic high-throughput sequencing and the Diting pipeline were utilized to investigate the microbial mechanisms involved in sediment C/N/S geochemical cycling during low-water-level regulation. The results reveal that the degree of pollution in LW sediment is lower compared to TW and ER sediment. LW sediment exhibits a higher capacity for pollutant degradation and elimination of black, odorous substances due to its stronger microbial methane oxidation, nitrification, denitrification, anammox, and oxidation of sulfide, sulfite, and thiosulfate. Conversely, TW and ER sediment showcase greater microbial methanogenesis, anaerobic fermentation, and sulfide generation abilities, leading to the persistence of black, odorous substances. Factors such as grit and silt content, nitrate, and ammonia concentrations impacted microbial metabolic pathways. Low-water-level regulation improved the micro-environment for functional microbes, facilitating pollutant removal and preventing black odorous substance accumulation. These findings provide insights into the microbial mechanisms underlying low-water-level regulation technology for sediment restoration in urban rivers.


Asunto(s)
Sedimentos Geológicos , Ríos , Sedimentos Geológicos/microbiología , Nitrógeno/análisis , Carbono , China
2.
J Transl Med ; 19(1): 496, 2021 12 07.
Artículo en Inglés | MEDLINE | ID: mdl-34876129

RESUMEN

Pulmonary fibrosis is the end stage of a broad range of heterogeneous interstitial lung diseases and more than 200 factors contribute to it. In recent years, the relationship between virus infection and pulmonary fibrosis is getting more and more attention, especially after the outbreak of SARS-CoV-2 in 2019, however, the mechanisms underlying the virus-induced pulmonary fibrosis are not fully understood. Here, we review the relationship between pulmonary fibrosis and several viruses such as Human T-cell leukemia virus (HTLV), Human immunodeficiency virus (HIV), Cytomegalovirus (CMV), Epstein-Barr virus (EBV), Murine γ-herpesvirus 68 (MHV-68), Influenza virus, Avian influenza virus, Middle East Respiratory Syndrome (MERS)-CoV, Severe acute respiratory syndrome (SARS)-CoV and SARS-CoV-2 as well as the mechanisms underlying the virus infection induced pulmonary fibrosis. This may shed new light on the potential targets for anti-fibrotic therapy to treat pulmonary fibrosis induced by viruses including SARS-CoV-2.


Asunto(s)
COVID-19 , Infecciones por Virus de Epstein-Barr , Fibrosis Pulmonar , Coronavirus Relacionado al Síndrome Respiratorio Agudo Severo , Virosis , Animales , Herpesvirus Humano 4 , Humanos , Ratones , Fibrosis Pulmonar/etiología , SARS-CoV-2
3.
Plant Physiol ; 184(4): 1853-1869, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-33020251

RESUMEN

The rapid and responsive growth of a pollen tube requires delicate coordination of membrane receptor signaling, Rho-of-Plants (ROP) GTPase activity switching, and actin cytoskeleton assembly. The tomato (Solanum lycopersicum) kinase partner protein (KPP), is a ROP guanine nucleotide exchange factor (GEF) that activates ROP GTPases and interacts with the tomato pollen receptor kinases LePRK1 and LePRK2. It remains unclear how KPP relays signals from plasma membrane-localized LePRKs to ROP switches and other cellular machineries to modulate pollen tube growth. Here, we biochemically verified KPP's activity on ROP4 and showed that KPP RNA interference transgenic pollen tubes grew slower while KPP-overexpressing pollen tubes grew faster, suggesting that KPP functions as a rheostat for speed control in LePRK2-mediated pollen tube growth. The N terminus of KPP is required for self-inhibition of its ROPGEF activity, and expression of truncated KPP lacking the N terminus caused pollen tube tip enlargement. The C-terminus of KPP is required for its interaction with LePRK1 and LePRK2, and the expression of a truncated KPP lacking the C-terminus triggered pollen tube bifurcation. Furthermore, coexpression assays showed that self-associated KPP recruited actin-nucleating Actin-Related Protein2/3 (ARP2/3) complexes to the tip membrane. Interfering with ARP2/3 activity reduced the pollen tube abnormalities caused by overexpressing KPP fragments. In conclusion, KPP plays a key role in pollen tube speed and shape control by recruiting the branched actin nucleator ARP2/3 complex and an actin bundler to the membrane-localized receptors LePRK1 and LePRK2.


Asunto(s)
Tubo Polínico/crecimiento & desarrollo , Tubo Polínico/genética , Proteínas Quinasas/metabolismo , Receptores Citoplasmáticos y Nucleares/fisiología , Transducción de Señal/fisiología , Solanum lycopersicum/crecimiento & desarrollo , Solanum lycopersicum/genética , Productos Agrícolas/anatomía & histología , Productos Agrícolas/genética , Productos Agrícolas/crecimiento & desarrollo , Regulación de la Expresión Génica de las Plantas , Genes de Plantas , Solanum lycopersicum/anatomía & histología , Plantas Modificadas Genéticamente/metabolismo , Tubo Polínico/anatomía & histología , Proteínas Quinasas/genética , Receptores Citoplasmáticos y Nucleares/genética , Transducción de Señal/genética
4.
J Am Chem Soc ; 141(13): 5497-5503, 2019 04 03.
Artículo en Inglés | MEDLINE | ID: mdl-30864793

RESUMEN

We located the unknown chirality-helicity equivalence in molecules with a chiral center, and as a consequence, the degeneracy of the S and R stereoisomers of lactic acid was lifted. An agreement was found with the naming schemes of S and R stereoisomers from optical experiments. This was made possible by the construction of the stress tensor trajectories in a non-Cartesian space defined by the variation of the position of the torsional bond critical point upon a structural change, along the torsion angle, θ, involving a chiral carbon atom. This was undertaken by applying a torsion θ, -180.0° ≤ θ ≤ +180.0° corresponding to clockwise and counterclockwise directions. We explain why scalar measures can at best only partially lift the degeneracy of the S and R stereoisomers, as opposed to vector-based measures that can fully lift the degeneracy. We explained the consequences for stereochemistry in terms of the ability to determine the chirality of industrially relevant reaction products.

5.
Plant Physiol ; 176(2): 1610-1626, 2018 02.
Artículo en Inglés | MEDLINE | ID: mdl-29187566

RESUMEN

In flowering plants, germ lines are induced from somatic meristems within reproductive organs. Within anthers, germinal cell initials first undergo several rounds of mitotic proliferation before synchronously entering meiosis. Our understanding of the progression and the molecular basis of this mitosis to meiosis transition is still limited. Taking advantage of the correlation between anther length and premeiotic germinal cell development in maize (Zea mays), we studied the transcriptome dynamics of germinal cells at three sequential stages, mitotic archesporial cells, enlarging pollen mother cells at the premeiosis interphase, and pollen mother cells at the early prophase of meiosis, using laser microdissection-based expression profiling. Our analysis showed that cells undergoing the mitosis-meiosis switch exhibit robust transcriptional changes. The three stages are distinguished by the expression of genes encoding transcription factor subsets, meiotic chromosome recombination proteins, and distinct E3 ubiquitin ligases, respectively. The transcription level of genes encoding protein turnover machinery was significantly higher in these three stages of germinal cells than in mature pollen, parenchyma cells, or seedlings. Our experimental results further indicate that many meiotic genes are not only transcribed, but also translated prior to meiosis. We suggest that the enlarging pollen mother cells stage represents a crucial turning point from mitosis to meiosis for developing germinal cells.


Asunto(s)
Regulación de la Expresión Génica de las Plantas , Meiosis/genética , Mitosis/genética , Proteínas de Plantas/genética , Transcriptoma , Zea mays/genética , Flores/genética , Flores/crecimiento & desarrollo , Flores/fisiología , Regulación del Desarrollo de la Expresión Génica , Células Germinativas de las Plantas , Meristema/genética , Meristema/crecimiento & desarrollo , Meristema/fisiología , Polen/genética , Polen/crecimiento & desarrollo , Polen/fisiología , Factores de Transcripción/genética , Zea mays/crecimiento & desarrollo , Zea mays/fisiología
6.
Plant Cell ; 26(6): 2505-2523, 2014 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-24938288

RESUMEN

The speed of pollen tube growth is a major determinant of reproductive success in flowering plants. Tomato (Solanum lycopersicum) STIGMA-SPECIFIC PROTEIN1 (STIG1), a small Cys-rich protein from the pistil, was previously identified as a binding partner of the pollen receptor kinase LePRK2 and shown to promote pollen tube growth in vitro. However, the in vivo function of STIG1 and the underlying mechanism of its promotive effect were unknown. Here, we show that a 7-kD processed peptide of STIG1 is abundant in the stigmatic exudate and accumulates at the pollen tube surface, where it can bind LePRK2. Antisense LePRK2 pollen was less responsive than wild-type pollen to exogenous STIG1 in an in vitro pollen germination assay. Silencing of STIG1 reduced both the in vivo pollen tube elongation rate and seed production. Using partial deletion and point mutation analyses, two regions underlying the promotive activity of the STIG1 processed peptide were identified: amino acids 80 to 83, which interact with LePRK2; and amino acids 88 to 115, which bind specifically to phosphatidylinositol 3-phosphate [PI(3)P]. Furthermore, exogenous STIG1 elevated the overall redox potential of pollen tubes in both PI(3)P-dependent and LePRK2-dependent manners. Our results demonstrate that STIG1 conveys growth-promoting signals acting through the pollen receptor kinase LePRK2, a process that relies on the external phosphoinositide PI(3)P.

7.
Plant Cell ; 26(9): 3538-55, 2014 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-25194029

RESUMEN

The tubular growth of a pollen tube cell is crucial for the sexual reproduction of flowering plants. LePRK1 is a pollen-specific and plasma membrane-localized receptor-like kinase from tomato (Solanum lycopersicum). LePRK1 interacts with another receptor, LePRK2, and with KINASE PARTNER PROTEIN (KPP), a Rop guanine nucleotide exchange factor. Here, we show that pollen tubes overexpressing LePRK1 or a truncated LePRK1 lacking its extracellular domain (LePRK1ΔECD) have enlarged tips but also extend their leading edges by producing "blebs." Coexpression of LePRK1 and tomato PLIM2a, an actin bundling protein that interacts with KPP in a Ca(2+)-responsive manner, suppressed these LePRK1 overexpression phenotypes, whereas pollen tubes coexpressing KPP, LePRK1, and PLIM2a resumed the blebbing growth mode. We conclude that overexpression of LePRK1 or LePRK1ΔECD rewires pollen tube growth to a blebbing mode, through KPP- and PLIM2a-mediated bundling of actin filaments from tip plasma membranes. Arabidopsis thaliana pollen tubes expressing LePRK1ΔECD also grew by blebbing. Our results exposed a hidden capability of the pollen tube cell: upon overexpression of a single membrane-localized molecule, LePRK1 or LePRK1ΔECD, it can switch to an alternative mechanism for extension of the leading edge that is analogous to the blebbing growth mode reported for Dictyostelium and for Drosophila melanogaster stem cells.


Asunto(s)
Extensiones de la Superficie Celular/metabolismo , Proteínas de Plantas/metabolismo , Tubo Polínico/enzimología , Tubo Polínico/crecimiento & desarrollo , Solanum lycopersicum/enzimología , Solanum lycopersicum/crecimiento & desarrollo , Actinas/metabolismo , Regulación de la Expresión Génica de las Plantas , Germinación , Solanum lycopersicum/genética , Fenotipo , Proteínas de Plantas/química , Plantas Modificadas Genéticamente , Tubo Polínico/ultraestructura , Unión Proteica , Transporte de Proteínas
8.
J Chem Phys ; 145(7): 074314, 2016 Aug 21.
Artículo en Inglés | MEDLINE | ID: mdl-27544112

RESUMEN

Three-center two-electron bonds are important for understanding electron-deficient molecules. To examine such a molecule, we produced a diborane(5) anion with a single-bridged structure upon electron bombardment during matrix deposition of Ar containing a small proportion of diborane(6). The diborane(5) anion was destroyed upon photolysis at 180, 220, 385, and 450 nm, but not at 532 nm. Moreover, the possible formation of neutral diborane(5) was observed upon photolysis at 385 and 450 nm, whereas neutral diborane(3) was observed upon photolysis at 180 and 220 nm. The observed line wavenumbers, relative intensities, and isotopic ratios of the diborane(5) anion agreed satisfactorily with those predicted by density functional theory calculations at the B3LYP/aug-cc-pVTZ level of theory. Thus, this method produced the boron hydride anion of interest with few other fragments, which enabled us to clearly identify the IR spectrum of the diborane(5) anion.

9.
Plant Mol Biol ; 86(4-5): 471-83, 2014 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-25168737

RESUMEN

Tubby and Tubby-like proteins (TLPs) play essential roles in the development and function of mammal neuronal cells. In addition to the conserved carboxyl (C)-terminal Tubby domain, which is required for their plasma membrane (PM) tethering, plant TLPs also possess an amino (N)-terminal F-box domain to interact with specific Arabidopsis Skp1-like (ASK) proteins as functional SCF-type E3 ligases. Here, we report the molecular characterization of Arabidopsis TLPs (AtTLPs). ß-Glucuronidase staining showed overlapped but distinct expression patterns of AtTLPs in Arabidopsis. Yeast two-hybrid assays further revealed that AtTLP1, AtTLP3, AtTLP6, AtTLP7, AtTLP9, AtTLP10 and AtTLP11 all interacted with specific ASKs, but AtTLP2, AtTLP5 and AtTLP8 did not. Subcellular localization observations in both Arabidopsis protoplasts and tobacco pollen tubes indicated that all GFP-AtTLP fusion proteins, except GFP-AtTLP8 which lacks the conserved phosphatidylinositol 4,5-bisphosphate binding sites, were targeted to the PM. Detailed studies on AtTLP3 demonstrated that AtTLP3 is a PM-tethered PIP2 binding protein which functions redundantly with AtTLP9 in abscisic acid (ABA)- and osmotic stress-mediated seed germination. Our results suggest that AtTLPs possibly work in multiple physiological and developmental processes in Arabidopsis, and AtTLP3 is also involved in ABA signaling pathway like AtTLP9 during seed germination and early seedling growth.


Asunto(s)
Ácido Abscísico/farmacología , Proteínas de Arabidopsis/genética , Arabidopsis/genética , Proteínas F-Box/genética , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Presión Osmótica , Secuencia de Aminoácidos , Arabidopsis/metabolismo , Proteínas de Arabidopsis/clasificación , Proteínas de Arabidopsis/metabolismo , Membrana Celular/metabolismo , Proteínas F-Box/metabolismo , Glucuronidasa/genética , Glucuronidasa/metabolismo , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/metabolismo , Microscopía Confocal , Datos de Secuencia Molecular , Mutación , Filogenia , Reguladores del Crecimiento de las Plantas/farmacología , Plantas Modificadas Genéticamente , Unión Proteica , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Semillas/genética , Semillas/crecimiento & desarrollo , Semillas/metabolismo , Homología de Secuencia de Aminoácido , Técnicas del Sistema de Dos Híbridos
10.
Phys Rev E ; 107(5-1): 054121, 2023 May.
Artículo en Inglés | MEDLINE | ID: mdl-37329040

RESUMEN

Since the problem of the residual entropy of square ice was exactly solved, exact solutions for two-dimensional realistic ice models have been of interest. In this work, we study the exact residual entropy of ice hexagonal monolayer in two cases. In the case that the external electric field along the z-axis exists, we map the hydrogen configurations into the spin configurations of the Ising model on the kagome lattice. By taking the low temperature limit of the Ising model, we derive the exact residual entropy, which agrees with the result determined previously from the dimer model on the honeycomb lattice. In another case that the ice hexagonal monolayer is under the periodic boundary conditions in the cubic ice lattice, the residual entropy has not been studied exactly. For this case, we employ the six-vertex model on the square lattice to represent the hydrogen configurations obeying the ice rules. The exact residual entropy is obtained from the solution of the equivalent six-vertex model. Our work provides more examples of the exactly soluble two-dimensional statistical models.


Asunto(s)
Frío , Hielo , Entropía , Electricidad , Hidrógeno
11.
Sci Total Environ ; 881: 163464, 2023 Jul 10.
Artículo en Inglés | MEDLINE | ID: mdl-37062316

RESUMEN

Phytoremediation is considered an effective technology for remediating antibiotic-contaminated water; however, its underlying mechanisms remain poorly understood. Therefore, this study investigated the phytoremediation potential of fluoroquinolone antibiotics (FQs) by different wetland plant species. The phytoremediation rates of ΣFQs were 46-69 %, and rhizosphere microorganism degradation (accounting for 90-93 %) dominated the FQ removal over that of plant uptake and hydrolysis. Dissipation of the FQs in the hydroponic system followed a first-order kinetic model. The joint action of the more powerful absorptive capacity of plants and stronger microbial degradation ability in the rhizosphere was the reason that Cyperus papyrus showed significantly higher FQ phytoremediation rates than the other three plant species, which implied that the plant species is a critical factor affecting phytoremediation efficiency. The FQ distribution in plant tissues decreased from root > stem > leaf, suggesting that FQs were more concentrated in the roots than in the aboveground tissues. Negative correlations between the diffusive gradient in thin films and root concentrations implied that these wetland plant species took up FQs mainly via active transport mechanism (requiring some vectors, perhaps via exudates); whereas, the process of root-to-stem transfer and upward transport represented passive transport, which mainly depended on transpiration. These results facilitate an improved understanding of phytoremediation processes and improve their future applications.


Asunto(s)
Contaminantes del Suelo , Humedales , Biodegradación Ambiental , Disponibilidad Biológica , Plantas/metabolismo , Antibacterianos/metabolismo , Fluoroquinolonas/metabolismo , Contaminantes del Suelo/análisis
12.
Bot Stud ; 63(1): 21, 2022 Jul 12.
Artículo en Inglés | MEDLINE | ID: mdl-35821129

RESUMEN

BACKGROUND: Blumea plants are widely distributed in the tropical areas of Asia, Africa, and Australia, especially tropical Asia. Limited studies left the taxonomy and infrageneric phylogeny of Blumea insubstantial. Here, a new species, Blumea chishangensis S. W. Chung, Z. H. Chen, S. H. Liu & W. J. Huang, from Taiwan is described, and an extended phylogeny is reconstructed to provide new perceptions of Blumea evolution. RESULTS: The new species is distinguished from B. hieraciifolia by the following features: leaf blade sparsely pilose or glabrescent (vs. silky villous), the leaves margins regularly remote mucronulate (vs. double serrate or dentate), capitula pedicelled (vs. capitula sessile or subsessile), and leaves basal rosette or sub-basal rosette and a few cauline (vs. mostly cauline). Phylogenetic analysis based on the ITS, trnL-trnF, and trnH-psbA regions places the new species in the subclade II in B. lacera clade and shows a close relationship with B. axillaris and B. oxyodonta. A key to Blumea species in Taiwan and the studied species in the subclade II is provided. Moreover, the evolutionary inferences of B. conspicua, B. linearis, and B. sinuata are first reported here. The paraphyly of B. formosana and B. sinuata are also revealed for the first time. CONCLUSIONS: Both morphological and molecular data support that B. chishangensis is a new species. Our phylogeny highlights the need for further taxonomic and evolutionary studies on Blumea.

13.
Neural Regen Res ; 17(9): 2014-2021, 2022 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-35142691

RESUMEN

Numerous studies have shown abnormal brain functional connectivity in individuals with Alzheimer's disease (AD) or amnestic mild cognitive impairment (aMCI). However, most studies examined traditional resting state functional connections, ignoring the instantaneous connection mode of the whole brain. In this case-control study, we used a new method called dynamic functional connectivity (DFC) to look for abnormalities in patients with AD and aMCI. We calculated dynamic functional connectivity strength from functional magnetic resonance imaging data for each participant, and then used a support vector machine to classify AD patients and normal controls. Finally, we highlighted brain regions and brain networks that made the largest contributions to the classification. We found differences in dynamic function connectivity strength in the left precuneus, default mode network, and dorsal attention network among normal controls, aMCI patients, and AD patients. These abnormalities are potential imaging markers for the early diagnosis of AD.

14.
Materials (Basel) ; 14(11)2021 May 29.
Artículo en Inglés | MEDLINE | ID: mdl-34072432

RESUMEN

The laser ablation synthesis in solution (LASiS) method has been widely utilized due to its significant prospects in laser microprocessing of nanomaterials. In this study, the LASiS method with the addition of different surfactant charges (cationic CTAB, nonionic TX-100, and anionic SDS) was used to produce Au NPs. An Nd:YAG laser system at 532 nm excitation with some synthetic parameters, including different laser fluences, ablation times, and surfactant concentrations was performed. The obtained Au NPs were characterized by UV-Vis spectroscopy, transmission electron microscopy, and zeta potential analyzer. The Au NPs exhibited the maximum absorption peak at around 520 nm for all samples. The color of Au NPs was changed from red to reddish by increasing the laser fluence. The surfactant charges also played different roles in the Au NPs' growth during the synthesis process. The average sizes of Au NPs were found to be 8.5 nm, 5.5 nm, and 15.5 nm with the medium containing CTAB, TX-100, and SDS, respectively. Besides, the different surfactant charges induced different performances to protect Au NPs from agglomeration. Overall, the SDS and CTAB surfactants exhibited higher stability of the Au NPs compared to the Au NPs with TX-100 surfactant.

15.
Front Plant Sci ; 12: 649720, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33777083

RESUMEN

The Mediator complex controls transcription of most eukaryotic genes with individual subunits required for the control of particular gene regulons in response to various perturbations. In this study, we reveal the roles of the plant Mediator subunits MED16, MED14, and MED2 in regulating transcription in response to the phytohormone abscisic acid (ABA) and we determine which cis elements are under their control. Using synthetic promoter reporters we established an effective system for testing relationships between subunits and specific cis-acting motifs in protoplasts. Our results demonstrate that MED16, MED14, and MED2 are required for the full transcriptional activation by ABA of promoters containing both the ABRE (ABA-responsive element) and DRE (drought-responsive element). Using synthetic promoter motif concatamers, we showed that ABA-responsive activation of the ABRE but not the DRE motif was dependent on these three Mediator subunits. Furthermore, the three subunits were required for the control of water loss from leaves but played no role in ABA-dependent growth inhibition, highlighting specificity in their functions. Our results identify new roles for three Mediator subunits, provide a direct demonstration of their function and highlight that our experimental approach can be utilized to identify the function of subunits of plant transcriptional regulators.

16.
PLoS One ; 15(6): e0234154, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32497144

RESUMEN

Phytohormones mediate most diverse processes in plants, ranging from organ development to immune responses. Receptor protein complexes perceive changes in intracellular phytohormone levels and trigger a signaling cascade to effectuate downstream responses. The in planta analysis of elements involved in phytohormone signaling can be achieved through transient expression in mesophyll protoplasts, which are a fast and versatile alternative to generating plant lines that stably express a transgene. While promoter-reporter constructs have been used successfully to identify internal or external factors that change phytohormone signaling, the range of available marker constructs does not meet the potential of the protoplast technique for large scale approaches. The aim of our study was to provide novel markers for phytohormone signaling in the Arabidopsis mesophyll protoplast system. We validated 18 promoter::luciferase constructs towards their phytohormone responsiveness and specificity and suggest an experimental setup for high-throughput analyses. We recommend novel markers for the analysis of auxin, abscisic acid, cytokinin, salicylic acid and jasmonic acid responses that will facilitate future screens for biological elements and environmental stimuli affecting phytohormone signaling.


Asunto(s)
Reguladores del Crecimiento de las Plantas/metabolismo , Protoplastos/citología , Transducción de Señal , Arabidopsis/citología , Biomarcadores/metabolismo
17.
Org Lett ; 22(13): 5014-5019, 2020 07 02.
Artículo en Inglés | MEDLINE | ID: mdl-32567863

RESUMEN

A catalytic asymmetric umpolung cross-Mannich reaction of cyclic ketimines is realized. This protocol provides an efficient methodology for the facile synthesis of chiral vicinal tetrasubstituted diamines in high yields with excellent chemo-, regio-, diastereo-, and enantioselectivities using cinchona-derived bifunctional organocatalysts (85-98% yield, up to >20:1 dr, and >99% ee).

18.
RSC Adv ; 10(23): 13700-13707, 2020 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-35493011

RESUMEN

"Calcium hydroxide [Ca(OH)2]" is a medicament frequently used for antimicrobial purposes in endodontic procedures, or it is used as a toxic-waste adsorbent in industry. Ca(OH)2 particles produced through conventional methods are size untunable and have a wide size distribution and polygonal shape. In this paper, a novel and facile approach involving template-mediated synthesis and two-step ion exchange is proposed for uniform size Ca(OH)2 composite particles generation. "Sodium-alginate (Na-alginate)" was used as a precursor, and monodisperse Na-alginate emulsions were formed through needle droplet or droplet microfluidic technology. After the first ion exchange step with the Ca2+ ions, "calcium-alginate (Ca-alginate)" particles were obtained. The Ca-alginate particles were intermediate reaction products and were designed to be the templates for ensuring the spherical shape and size of products. The OH- ions were used for the second ion exchange step to fabricate Ca(OH)2 composite particles. The results revealed that the Ca(OH)2 composite particles were size tunable, had a spherical shape, and were monodisperse (with a relative standard deviation of less than 8%). The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay revealed that the Ca(OH)2 composite particles were potential biocompatible materials.

19.
Orthop Surg ; 11(6): 1173-1179, 2019 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-31823497

RESUMEN

OBJECTIVE: To evaluate clinical and radiological outcomes of proximal femoral nail anti-rotation (PFNA-II) devices and demonstrate the effectiveness of PFNA-II for the treatment of basicervical fractures in elderly patients. METHODS: A retrospective review of all patients treated with PFNA-II for a proximal femoral fracture between January 2013 and February 2017 at three different institutions (Shanghai General Hospital, Shanghai Punan Hospital and Shanghai Seventh People's Hospital) was conducted. The X-ray films were strictly reviewed by three trauma surgeons and a professional radiology doctor. Patients over 60 years of age who met the following criteria were included: (i) sustained low-energy trauma; (ii) a two-part fracture; (iii) fracture line located at the base of the femoral neck and that was medial to the intertrochanteric line and exited above the lesser trochanter but was more lateral than a classic transcervical fracture. Follow-up time should be longer than 6 months. A total of 52 patients who met the inclusion criteria were selected. The average age at diagnosis was 75.1 years (range, 63-91 years); 13 patients were men and 39 were women. The same proximal femoral nail anti-rotation devices and the same surgical procedures were applied to all patients. Postoperative radiographic union time and modified Harris hip scores were used as major indicators for evaluating the effectiveness of surgery. RESULTS: The average follow-up period was 22.5 months (18.5, 23.9, and 21.2 months, respectively) and radiographic unions were observed at an average of 19.6 weeks (range, 12-28 weeks). The patients were evaluated immediately after surgery, as well as 6 weeks, 3 months, 6 months, 1 year, and 2 years postoperatively. Of the 49 patients, 38 had good reduction qualities (75.5%), 9 acceptable (18.3%), and 3 poor (6.1%). Radiographic union was confirmed in all fractures at an average of 19.6 weeks (range, 12-28 weeks). The mean Harris hip score was 84.9 (range, 65-99): excellent in 9 patients (18.36%), good in 30 (61.22%), medium in 8 (16.32%), and poor in 2 (4.08%). Slight persistent pain occurred in 3 patients, but these patients could still walk with the help of a cane. Two patients had symptoms of excessive telescoping. Eight patients experienced postoperative medical complications, mainly pneumonia and urinary tract infection. CONCLUSION: Based on the clinical and radiological outcomes, the PFNA-II devices provide strong rotational stability and excellent clinical prognosis, and are an appropriate treatment option for basicervical proximal femoral fracture in elderly patients.


Asunto(s)
Fracturas del Fémur/cirugía , Fracturas del Cuello Femoral/cirugía , Fijación Intramedular de Fracturas/métodos , Anciano , Anciano de 80 o más Años , Clavos Ortopédicos , Evaluación de la Discapacidad , Femenino , Fijación Intramedular de Fracturas/instrumentación , Humanos , Fijadores Internos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Rotación
20.
Materials (Basel) ; 11(12)2018 Nov 27.
Artículo en Inglés | MEDLINE | ID: mdl-30486400

RESUMEN

In this paper, we report the synthesis of iron silicide and ß-iron disilicide nanowires with chemical vapor deposition; remarkably, the latter has drawn much attention but has seldom been achieved. We also propose the formation mechanisms for the two phases. To investigate the effects of the growth parameters on compositions and morphologies of the iron silicide nanowires, we changed and studied the reaction time, substrate temperature, position of samples, and pressure. The reaction concentration was found to be altered by all of the parameters; thus, we observed different nanowires in terms of morphologies and compositions with scanning electron microscopy. To confirm the growth direction and crystal structure of the nanowires, we conducted x-ray diffraction and high-resolution transmission electron microscopy studies. With the potential of being utilized as circuit elements in electronic devices for Schottky barriers, ohmic contacts, and interconnection among silicon-based transistors, the silicide work at nanoscale is beneficial for nanoelectronics. Understanding the effects of these growth parameters facilitates the control of nanowire growth with better quality.

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